Mmm, but according to the book angels are sexless unless they make the effort. So there is that undercurrent of potential there. And in the bible there are also the Nephilim - from the ‘sons of God’ mating with the ‘daughters of Earth'. Obviously interpretation of sons of God is open to ambiguity. Fallen angels seems to be the popular interpretation. Actual angels is another interpretation, given that sons of God is implied elsewhere in the bible to be angels. So maybe possible…
Besides which, it is Gaiman and Pratchett's creation - if Pratchett endorsed that interpretation and Gaiman now sees it that way, it's their story! Although, having said that, I suspect that that particular scene is not all it seems. There are so many loose ends in season two, the whole thing feels like a set up, and some of the things that feel as if they got dropped for no reason or just plain clumsy, just could be that way for a reason. In that scene's case the timing feels off, and the clock (continuity error maybe…), I swear there is something else going on and it'll be revealed in Season three. Also Maggie is a demon (I'm probably wrong on that one…) I really want season threee…
Although, I actually did like the hints of Crowley/Aziraphale when I read the book decades ago… So I would be happy with a romantic relationship between them. And after all Aziraphale does like the food and drink related pleasures of the world so much. I do have some sympathy with people preferring their relationship to be asexual. I can remember being furious when new Who made the Doctor fall in love with a human, which I thought was ridiculous! But for me, I do want to see Crowley and Aziraphale's relationship on screen and I do want to think they end up in love, whatever form that takes. So I hope we get season three.